High octane number motor fuel



atented eh. 4, 1941 srrss or cs HIGH OCTANE NUMBER MOTOR FUEL Pharis Miller, Elizabeth, and August Y. Mottlau, Clark Township, Union County, N. .L, assignors to Standard Oil Development Company, a corporation of Delaware No Drawing.

- 7 Claims.

octane aviation fuels. The fuel compositions of the present invention comprise a suitable base motor fuel, a secondary aromatic amino compound and tetra ethyl lead.

It is well known in the art to prepare various fuels and fuel blends having high anti-knock characteristics as measured by high octane number. These fuels are usually prepared by adding knock suppressing agents, as for example, tetra ethyl lead, carbonyls of iron and nickel, to suitable petroleum base fuels. High octanenumber fuel blends are also prepared by adding to a suitable petroleum base fuel various blending substances having high octane number, as for example, iso-octane', iso-pentane, various olefins and the like, as well as amino compounds, as for example, aniline and various other primary aromatic amines. By these methods it has been possible to prepare satisfactory fuels having desirable volatility characteristics and having octane numbers in the range from about to as measured by the motor method of the S. A. E. Committee of Fuel Research and of the A. S. T. M. However, these methods have not been entirely satisfactory for the preparation. of fuels of desirable volatility characteristics and having octane numbers inthe range from 95 to and higher,

particularly fuels having octane numbers in the range from to, 120. For example, the amount of any knock suppressing agent which may be added is limited due to inherent disadvantages produced by using an excessive quantity. Likewise, the amount of any high octane number blending substance which may be added is limited by adverse effects on the volatility charact'eristics of the fuel as well as by the expense involved in producing suitable high octane number blending substances.

Furthermore, the use of knock suppressing agents, especially tetra ethyl lead, in a fuel in conjunction with fuel blending substances, as for example, primary aromatic amines, has not been satisfactory since these materials when used together offset the improvement secured when they are used alone. For example, it is known that a fuel blend comprising a suitable base fuel, a knock suppressing agent, as for example, tetra ethyl lead, and a high octane number blending substance, as for example, a primary aromatic amine, will be inferior in anti-knock characteristics as compared to either a fuel blend comprising a suitable base fuel and tetra ethyl lead or a similar suitable base fuel and a primary aromatic amine. This is extremely unfortunate since high octane number fuels are at a premium, especially high octane number aviation fuels. Thus, when Application November 25, 1938, Serial No. 242,272

it is considered that optimum engine performance is secured by utilizing fuels having a pre-determincd'specified volatility character usually measured in terms of Engler distillation, that these volatility characters vary with climatic conditions and with the particular engine and service for which the fuel is to be used and'that the fuel must'nec'essarily have'high anti-knock characteristics, thedifiiculty involved in preparing a suitable fuel'is readily apparent.

We have now discovered an economical fuel blend which has unexpected desirable characteristics. Our fuel composition comprises-a base petroleum fuel which may-be blended to have optimum predetermined volatility characteristics, a relatively small quantity of an added blending substanceselected from the 'class'of'secondary aromatic amines and tetra ethyl lead. The

amount of the secondary aromatic amine used in conjunctionwith lead is relatively small as compared to the base fuel with the result that the volatility characteristics of the base fuel will not be disturbed while the octane number characteristics of the base fuel will be materially increased. Thus fuel compositions having high octane numbers and having optimum volatility characteristics may be economically and readily prepared. Preferred fuel blends of our invention are fuels having optimum volatility characteristics and having octane numbers above 95 in the range from 100 to and higher.

Suitable blending substances for the preparation of the fuels of the present inventionare selected from the class of secondary aromatic amines. The structural formula of compounds of this class may be represented as follows:

If Q) in which R" represents an alkyl or an aryl group. These materials are termed N-alkyl amino benzenes or N-aryl amino benzenes. Suitable substances of this class are, for example, N-methyl amino benzene, N-ethyl amino benzene, N-phenyl amino benzene, N-propyl amino benzene, N-iso benzenes in which the alkyl group contains from 1 to 5 carbon atoms in the molecule, as for example, N-ethyl amino benzene and N-isoamyl amino benzene. Especially desirable results are secured when the N-alkyl group is of a branched chain structure, as for example, N-isoamyl amino benzene or N-tertiary butyl amino benzene.

Other especially desirable blending substances are secondary aromatic amines having at least one alkyl group attached to the aromatic ring,

in which R may represent an alkyl or an aryl group and in which R1" may represent an alkyl group or hydrogen.

These substances are termed N-alkyl amino alkyl benzenes. Preferred substances of this class are N-alkyl amino alkyl benzenes having one or two alkyl groups containing from 1 to 5 carbon atoms attached to the aromatic ring, examples of which are N-tertiary butyl amino isobutyl benzene, N-isoamyl amino, isoamyl benzene. N-phenyl amino para-tertiary amyl benzene and 4,4',di-tertiary amyl diphenyl amine. Especially desirable results are secured when utilizing compounds containing branched alkyl groups of the primary or tertiary structure attached to the aromatic ring, as for example, N-tertiary butyl amino benzene and N-ethyl amino isoamyl benzene.

The blending substances of the present invention may be added to the base fuel in any desirable proportion. The quantity added will depend upon the particular base fuel used, as well as upon the blending substance employed and the amount of tetra ethyl lead used. In general, it is and have a clear octane number from about 65 to 90, preferably above '75. In preparing high octane number aviation fuels, the base fuel should boil in the range from 100 to 300 F. and have a base octane number preferably from about 75 to 85.

In order to further illustrate the invention, the following examples are given which should not be construed as limiting the invention in any manner whatsoever.

EXAMPLES An aviation base fuel comprising 50% of a standard aviation gasoline, 40% of 2.2.4 trimethyl pentane and 10% isopentane had the following inspections:

Various fuel compositions were prepared using this base aviationfuel and various blending substances with and without tetra ethyl lead. The octane numbers were determined on the various blends using the C. F. R. motor method. In the first series of tests, blending agents of the class of primary aromatic amines were used. The results of these tests were as follows:

Table 2 I 0. N. Clear 0. N. Base fuel+ (no TEL) 2 cc. TEL substance used) Base fuel 84. 7 96.8 12. 1

0. N. im- 7 0. N. in 0. N. im- Total 0. N.

. 0. N. provement 25 provement improvement 331 223? Base fueH-blending substance of blend due to 2 cc blend due to TEL a m v I y (no TEL) blending w due to and blending, .3 substance TEL agent TE L alone 2%.anlline 89. 7 5. 0 97. 9 8. 2 13. 2 l. 1 2% o-toluid inc--. 88. 0 3. 3 95. 1 7. 1 l0. 4 -l. 7 2'7 m-toluidine 89. 8 5. l 97. 7 7 9 13. 0 +0. 9 2% p-tO1l1ld1ll0 91. s c. 8 96.1 a c 11. 4 -o. 1 2% amino o-ethyl benzeu 86. 6 1. 9 96. 0 8. 4 10.3 l. 8 2% amino p-tertiary am 1 benzene. 87. 8 3. l 97. l 9. 3 12. 4 +0. 3 2% amino 1:3 dimethyl enzene 87. 5 2. 8 96. 1 7. 0 10. 4 -1. 7 2% o-amino 1 methyl isopropyl benzenc-. 87. 5 2. 8 97. 5 l0. 0 12. 8 +0. 7

preferred to use from about to 5%, preferably from about 1% to 3%, of the blending agent in conjunction with from 1 to 10 cc. of

tetra ethyl lead to secure high octane number aviation gasolines. However, in the preparation of motor fuels for non-aviation uses, it may be desirable to employ from 0.1% to 1% of the blending substance in conjunction with from about 1 to 2 cc. of lead.

The quantity of tetra ethyl lead added will likewise depend upon the base fuel being used, the particular blending substance employed, as well as upon the octane number desired. In general, it is preferred to use from to 4 cc. of tetra ethyl lead, preferably from 2 to 3 cc. of tetra ethyl lead. Y

The base fuel may be any motor fuel of suitable fuel should boil in the range from 100 to 420 F.

From the above data it is readily apparent that it is not economically justified to utilize a primary aromatic amine in combination with tetra ethyl lead in order to improve the octane number of petroleum base fuels. In every instance the octane number of 2% blend as shown in column 2 was from about 2 to 7 octane numbers higher than the octane number of the base fuel. However, the octane number improvement secured by adding 2 cc. of tetra ethyl lead to the 2% blend as shown by column 4 is only from about 5 to 10 octane numbers higher as compared to 12.1 octane numbers improvement secured when using tetra ethyl lead in the absence of the blending substance. Thus, the total octane number improvement secured when utilizing tetra ethyl lead and 2% of a primary aromatic amine is in many cases below the improvement secured when utilizing tetra ethyl lead alone.

Table 1 Reid vapor pressure pounds '7 Initial boiling point F 100 55% distilled F 203 Final boiling point F 260 Gravity A. P. I 68 C. F. R. octane number M. M 84.7

Table 3 Octane numbers were determined The above data demonstrate that considerably higher octane number fuel compositions may be secured by utilizing a relatively small percentage of a secondary aromatic amine in conjunction with tetra ethyl lead. It further demonstrates that the amount of secondary aromatic amine utilized should be in the range from 1% to 5%, preferably in therange from 1% to 3%.

The secondary aromatic amines are also advantageous in that they have extremely low freezing points and are also entirely soluble in gasolines at low-temperatures. The secondary aro-' 0. N. improve- Clear 0. N. Base fuel+ ment due to (no TEL) 2 cc. TEL TEL (no blending substance used) Base fuel 84. 7 96. 8 12. 1

0. N. im- O. N. im- 0. N. 1111- Total 0. N. O. N. provement g gdg provernent improvement $3 2 33; Base iuel-l-blending substance or blend 2 cc. 2 cc of blend due to TEL agent and (no TEL) blending 2 cc. and blending TEL over substance TEL agent TEL alone 27 N'etbyl amino benzene 86. 3 1.6 100+ 13. 7 15.3 +3. 2 2 N-n propyl amino. benzene... 85. 0.8 100+ 14.5 15.3 +3.2 2%'N-isoamyl amino benzene 83. 4 -1 3 100+ 16. 6 15.3 +3.2 1% N-mctliyl 1 amino 4 methyl benzene.... 98. 6 13. 9 +1. 8

From the above data it is readily apparent that secondary aromatic amines do not improve the octane number of the base fuel to any appre ciable extent and in many cases actually act as knock inducing agents. However, when these substances are used in conjunction with tetra ethyl lead, unexpected desirable high octane number fuel compositions are secured. Thus, the total octane number improvement secured When utilizing a secondary aromatic amine in conjunction with lead is considerably greater than the total octane number improvement secured when using a primary aromatic amine in conjunction with lead notwithstanding the fact that the primary aromatic amine is a knock suppressing agent'and the secondary aromatic amine is in many cases a knock inducing agent.

Additional tests were made using a 74 octane number gasoline as a base fuel when using various percentages of secondary aromatic amines. The results of these tests were as follows:

Table 4 provemen a as: test? (no TEL) mg stance used) Base fuel 74 88 14 O N. im-

Total 0 N.

. provement Base fuel blending i g g gggfigg of blending Substance 3 cc. TEL and blending P fi ff and agent Over TEL alone 1% N-methyl amino benzene. 90. 9 16. 9 2. 9 3% N-methyl amino benzene. 93.5 19. 5 5. 6 5% N-methyl amino benzene. 92.1 18.1 4. 1 1% N-ethyl amino benzene... 89. 7 15. 7 1. 7 3% N-ethyl amino benzene. 92. 4 18. 4 4. 4 5% N ethyl amino benzene. 90. 9 l6. 9 2. 9

matic amines are also characterized by the fact that they are not soluble in water, further in creasingtheir desirability. Thus, motor fuels containing these substances may readily be used at high altitudes, at relatively low temperatures and will not be washed out with water. Although it is preferred to add the secondary aromatic amine to'a fuel containing tetra ethyl lead before introducing the fuel into the engine, the invention is not to be restricted in this manner.

For example, it may be desired to inject desirable quantities of the secondary aromatic amine into the combustion chamber or at any other intermediate point.

The present invention is not to be limited by any theory or mode of operation, but only by the following claims in which it is desired to claim all novelty insofar as the prior artpermits.

We claim:

1. An improved high octane number motor fuel comprising a gasoline base fuel having a clear octane number above about 75, 0.5 to 10 cc. of tetra ethyl lead per gallon of the fuel, and from 1 to 5% of a compound having the structural formula:

III R1 R1 N R1 I 1 R1 in which R represents a hydrocarbon radical selected from the class consisting of iso-allqrl-and alkyl-phenyl radicals, and R1 represents hydrogen and alkyl substituents in the benzene nucleus attached to N.

2. A high octane number motor fuel having a clear octane number above about '75 comprising a gasoline hydrocarbon base fuel, 0.5 to 10 cc. per gallon of tetra ethyl lead. and an N-iso-alkyl amino benzene in the concentration from 1% to 5%. i

3. A composition in accordance with claim 2, in which a branched alkyl group is attached to the benzene nucleus in said N-alkyl amino benzene.

4. An improved aviation fuel having a high octane number comprising a gasoline base fuel.

about '15, 0.5 cc. to 10 cc. per gallon of tetra-ethyl lead, and N-isobutyl amino benzene present in the concentration from about 1% to 5%.

'1. An improved aviation fuel comprising a hydrocarbon base fuel having a clear octane number oi at least about 75, containing a substantial quantity of iso-octane and boiling substantially within the range of 100 F. to 420 F., and blended therewith from 0.5 cc. to 10 cc. of tetra ethyl lead per gallon of fuel, and an N-iso-alkyl amino benzene in a concentration from about 1% to 5%.

PHARIS MILLER. AUGUST Y. MOITLAU. 

